Sagger



July 17, 1928. 7 1,677,452

J. A. JEFFERY SAGGER Filed Jan. 1926 Patented July 1' 7, 1928,-

UNITED STATS JOSEPH A. JEFFERY, 015 DETROIT, MICHIGAN, ASSIGNOR TOCHAMPION PORCELAIN COMPANY, A CORPOTIQN OF MICHIGAN.

SAG GER.

My invention has for its object to provide ceramic bodies which willneither decompose nor bend at relatively high temperatures. Theinvention particularly relates k1ln 6 furniture, such as saggers,furnace'linings, and other refractory bodies or articles which aresubjected to high temperatures and portions of which are so suspendedorsustained that they are subjected to bending stresses, 10 either bytheir own weight alone or by the .added weight of sustained bodies.

Ceramicbodies formed of alumina, silica and a flux, in properproportions, may be made quite refractory, and do not decompose at hightemperatures, but such bodies ma be bent out of shape by comparativelylitt e strain at high temperatures. Bodies formed of silicon carbide arehighly refractory and retain their strength well at high temperatures;but the silicon carbide de composes at high temperatures suificiently togive oif a troublesome carbonaceous gas. My improved bodies or articlesare made of a refracto alumina and silica compound or simi ar 'materialwith layers or portions of silicon carbide in such amounts and suchlocations as necessary to provide 40 similar to Fig. 1, showing aslightly modified form of sagger; Fig. 4 is a section of a slabembodying my invention and useful for a variety of purposes.

The sagger 10, shown n Fig. 1, has side walls 11, which are shown brokenOE and which may be of any desired .height, and a bottom 12. t The sidesare shown as being made en- I tirely of a refracto alumina-silicacomposition 13, while the ttom is shown partly of the same material asthe sides and partly of silicon carbide 14. The sagger is adapted ,torest upon the walls 15 of a subjacent sagger, c ay pads 16 beinginterposed be- 65 tween the two saggers. This leaves the botthe bottomrequires suflicient stifiness to support its own weight and the weightof any articles placed in the sagger. Therefore, while the side wallsare strong enough without reinforcement, the bottom is strengthened bythe stifiening layer of silicon carbide.

In the example shown, the layer of silicon carbide is lenticularinshape, so as to be thickest where the greatest strength is needed, andis completely covered on the upper side with the other refractorymaterial, so that no carbonaceous fumes will es' cape from the siliconcarbide into the sagger and discolor any ware therein.

In order to prevent the escape of carbonaceous gas downward into thelower sagger, the bottom of the layer of silicon carbide may be coveredwith refractory material similar to that which forms the rest of thesagger, or it may be glazed. It is diflicult, if not impossible, toapply a satisfactor glaze directly to silicon carbide, and I prefer tocover the bottom of the carbide with a thin layer 17 of the otherrefractory material, and then apply. a glaze 18 to this material, so asto make it gas tight. The thickness of layers 17 and 18 are exaggeratedin Fig. 2 for purposes of illustration.

While ordinary fireclay or other refractory clay might be employed forthe main body of the article, such materials shrink, when fired, to suchan extent that it is difficult to form a satisfactory union between themand the silicon carbide. Therefore I prefer to use an alumina-silicacompound which is anhydrous, or which contains so little water that itsshrinkage is comparatively negligible. 'Materials satisfactory for thispurpose are artificial sillimanite, minerals of the sillimanite group,and other compounds of alumina and silica, such as dumortierite, which,when fired to the neces sary temperature, produce artificial sillimaniteor mullit'e without great change in volume.

Among the materials mentioned, andalusite and dumortierite areparticularly desirable, as they may be applied green to the siliconcarbide and, upon firing, will not change materially in volume, evenwhen fired above the point where they are transformed into artificialsillimanite. Furthermore, they make an excellent foundation for a,

glaze. Andalusite, with the admixture of such plastic and fluxingmaterials as necessary, is the preferred form of refractory for the mainbody of the article.

- In Fig. 3, a sagger 20 is shown which is similar to the saggershown inFig. 1 except that it has the layer'of silicon carbide 21 extendedentirely across the bottom so that its edges 22 rest upon the supports23. It will be clear that the thickness, extent and location of thereinforcing portions of silicon carbide will be dependent upon thestrains which the article is intended to with-' stand, and that the examles given in Figs; 1 and 2 are by way of i1 ustration.

In Fig. 4 there is shown a slab composed of similar layers 24 of thealumina-silica compound and an intermediate layer 25 of silicon carbide.In the illustration, the three layers are shown of substantially equalthickness, but it is clear that any of the layers may be made thicker orthinner as the intended use may make advisable, and that many otherforms and arrangements of the two materials may be made to meet demandsof various uses to which the articles are to be put.

The saggers shown are very well adapted for the firing of porcelaineousbodies, particularly when such bodies are white and discoloration wouldbe detrimental, but this particular use is merely one for which theinvention is particularly adapted, and my invention is capable of a widevariety of forms and uses within the terms of the appended claims.

What' I claim is:

1. A silicon carbide body covered by a refractory alumina-silicacompound which does not change materially in volume from the green statein which the compound is applied to the body when fired to a hightemperature, the layer of the alumina-silica compound being ofsuflicient thickness to be injured by any material change in volumerelative to the silicon carbide.

2. A silicon carbide body covered by a refractory material of which thegreater part is a mineral aluminum silicate which, upon firing to a hightemperature, is transformed into artificial sillimanite without materialchan e in volume.

3. A silicon car ide body covered by a' carbide.

by said refractorfy 0 fired to a high temperature, reinforced, at

points where it is to be subjected to bending at high temperatures, byalayer of silicon into artificial sillimanite without material change involume, reinforced, at points where it is intended to withstand bendingstrain at high temperatures, by a layer of silicon carbide.

8. A refractory body composed chiefl of andalusite and reinforced, atpoints w ere it is to be subjected to bending strain at hi htemperatures, by a layer of silicon carbi e.

9. A refractory alumina-silica body which does not chan e materially involume when fired to a big temperature, reinforced, at points where itis to be subjected to bending at high temperatures, by a layer ofsilicon carbide, the layer of silicon carbide being surrounded by saidrefractory "material. o

10. A sagger formed of a refractor material which does not changemateria y in volume when heated to a high temperature and which does notdecompose when heated to a high temperature, and having its bottomreinforced'by a layer of silicon carbide covered by said material.

11. A sagger formed of a refractory alumine-silica compound which doesnot change materially in volume when fired to a high temperature, andhaving its bottom rein orced by a layer of silicon carbide covered bysaid material.

12. A sagger made of a refractory material composed. chiefly of amineral 8.1111111.

num silicate which upon firing is transformed into artificialsillimanite without material change in volume, the bottom of the saggerbeing reinforced by a layer of silicon carbide, the said layer beingcovered by said refractory materia 13. A sagger formed. from arefractory material composed chiefly of andalusite bottom of the saggerbeing reinforced by a layer of silicon carbide covered by saidrefractory material. 1

14. A sagger formed from a refractory alumina-silica compound which doesnot change materially in volume upon firing to a high temperature, thebottom of the sagger being reinforced by a lano-convex layer of siliconcarbide, said layer being covered material.

15. A saggerrmed from a refractory alumina-silica compound which doesnot change materially in volume upon firing to a high temperature, thebottom of the sagge'r being reinforced by a lano-convex layer of siliconcarbide, said layer being covered by said refractory material, the saldrefracthe i tory material being glazed at points wher it is thin overthe silicon carbide.

16. A sagger formed from a refractory material composed chiefly ofandalusite, and

having its bottom reinforced by a plane posed of a refractory materialformed' chiefly from andalusite. and having its hot-- tom reinforced bya layer of silicon carbide covered by said refractor material, the saidlayer of silicon carbide eing plane-convex with its convex side upwardand with its lower side covered by a comparatively thin layer of saidrefractory material.

In testimony whereof, I have hereunto signed my name to thisspecification.

- JOSEPH A. JEFFERY.

